Traditionally, sensitive documents have been printed on special paper that contains a physical watermark or electronically, e.g., as Portable Document Files (PDF), with an embedded digital watermark and accompanied by one or more access policies. Access policies control how a user can use the file. As an example, an access policy can allow the recipient to open the attached file only once before the policy is revoked, thus preventing the recipient from opening the file multiple times.
The paper distribution process is often costly and time-consuming. For example, to prepare for the distribution of four or five movie scripts to twenty readers to review over a weekend, a movie studio needs to replicate each script twenty times, bind each script, and hand deliver the scripts to each reader by the close of business on Friday before the weekend. On the following Monday, to ensure the scripts are not leaked to unauthorized third parties, the studio needs to collect and account for each of the scripts distributed.
Even though emailing scripts as PDF documents improves the distribution process, there are limitations with this form of distribution. Often the policies are managed by a policy server, and the policies embedded in the PDF documents require constant Internet connectivity to check with the policy server to ensure that the user is complying with the policy. Hence, this process is unreliable if a recipient does not have constant Internet access.